N-alkyl-n&#39;-(p-hydroxyphenyl) ureas



Patented Dec. 22, 1953 N -ALKYL-N'- (P-HYDROXYPHENYL) UREAS Eugene P. Hill, Birmingham, and 'David 0. De

Pree, Royal Oak, Mich., assignors torEthyl Corporation, New .York, N. Y., a corporation of Delaware N Drawing. Application September 16,1953, Serial No. 380.7604

4 Claims.

been described heretofore. This material possesses no utility in the field of oxidation inhibition. We have discovered, however, that by substituting the free amine of N-p-hydroxyphenyl urea with an alkyl group We obtain a class of substances which are powerful gasoline antioxidants. So far as we are aware it has not previously been known that the mere addition of an alkyl group to an otherwise inactive compound. would produce thereby a material which would prevent deterioration of petroleum hydrocarbons by the action of oxygen.

Therefore it is an object of our invention to provide a new class of antioxidant materials useful in protecting petroleum hydrocarbons from deterioration in the presence of oxygen or air. In particular it is an object of our invention to provide a new class or" materials which prevent the deterioration of motor fuels by oxygen.

In accordance with our invention we provide new ureas which contain the structure wherein R is an alkyl group containing from 5 to 12 carbon atoms inclusive. Examples of such alkyl radicals include n-amyl, hexyl, heptyl,

. octyl, nonyl, decyl, undecyl and dodecyl and 3 branched isomers thereof such as for example 2- methylhexyl, isoamyl, Z-methylpentyl, isoheptyl, isooctyl and the like.

The free amine from which our compounds may be considered as being derived, in addition to being inactive as an antioxidant, possesses a low degree of solubility in petroleum hydrocarbons. However, by substituting an alkyl group on the free amine nitrogen, in accordance with our invention, we not only increase the solubility of our invention, and in these examples all parts and percentages are by weight.

EXAMPLE "I N-(mixed amyl) -.N' ('p .-hydroa:yphenyl)- urea-To a vessel provided with an agitator, means for returning reflux to the reaction vessel, means for introducing liquid reactants, and means for supplying heat was added 100 parts of of p-aminophenol andBOOparts of toluene. This mixture was heated to a temperature of C. and 101 .parts of (mixed) :amylisocyanates was added over a period of one and one-quarter hours. At the end of the addition the mixture was heated for an additional period of 30 min,- utes. The reaction mixture containing the product as a suspended ,solid was filtered andthe N.- (mixed amyl .-N-(p hydroxyphenyl) urea was recovered. having a..me1 ting pointof 180 C. with decomposition.

EXAMPLE II N-n-octyl-N'- (p-hydroryphenyl) urea.-In accordance with the procedure of Example I, 100 "parts of p-aminophenol in 300 parts of toluene was treated with 142 parts of n-octylisocyanate. This product, N-n-octyl-N'-(p-hydroxyphenyl) urea, has a melting point of 131 C.

EXAMPLE III N n-dodecyl-N'-(p-hydrozcyphenyl) urea-In accordance with the procedure of Example I, 100 parts of p-aminophenol in 300 parts of toluene was treated with 188 parts of dodecylisocyanate to produce N-n-dodecyl-N'-(p-hydroxyphenyl) urea having a melting point of 142 C.

Likewise other embodiments of the compounds of our invention are prepared. Thus when the following alkyl isocyanates are reacted with paminophenol the corresponding N-alkyl-N'-(phydroxyphenybureas are produced; n-amylisocyanate, 2-methylbutylisocyanate, n-hexylisocyanate, 2-methylpentylisocyanate, B-methylpentylisocyanate, n-heptylisocyanate, 2-methylhexylisocyanate, 3-methy1hexylisocyanate, n-octylisocyanate, isooctylisocyanate, nonylisocyanate, decylisocyanate, undecylisocyanate, dodecylisocyanate, and the like.

The compounds of our invention ar excellent antioxidants and we have illustrated this property in the table, wherein we have listed the results obtained by determining the oxidation stability of gasoline according to the induction petion of specific examples of the novel compounds riod method, AS'I'M designation: D525-46, as

3 fully described in Part III-A, AS'I'M Standards for 1946. We have employed gasoline in this determination since it is representative of an important class of industrial products which are susceptible to deterioration, and for which it is important to provide stabilizing materials. The column headed IPI lists the induction period increase, in minutes, over that of the gasoline in the absence of the antioxidants of our invention. That is, under the conditions of test, each gasoline exhibits a period, typical of the gasoline, wherein oxygen is not absorbed.

In the presence of our inhibitors this period is increased by the amount listed under IPI. The lack of effectiveness of N-(p-hydroxyphenyDurea is shown by compound No. 6 in the table. Also listed in the table are the materials N-n-butyl- N-(phydroxyphenyl)urea and N-n-octadecyl- N'-(p-hydroxyphenyl)urea to indicate the unusual effect of the alkyl chain on the antioxidant effectiveness of the class of chemicals. While the latter two materials, which have shorter and longer N-alkyl groups respectively than the materials of this invention, are mild antioxidants, the materials of our invention are on the order of 200 to 300 per cent more efiective. Thus by the mere increase by one carbon atom of the N- alkyl group of compound 4 a material nearly three times as effective (compound 1) is formed. Thus, we have discovered a series of compounds wherein a non-linear relation between chain length and properties exists. Either increasing or decreasing the chain reduces materially the effectiveness. The effect of ring closure of the alkyl group likewise results in diminished gasoline antioxidant effectiveness. Thus, the closely related material N-cyclohexyl-N'-(p-hydroxyphenyl urea has an IPI of only 390, less than any of the materials in the group of alkyl, acyclic, compounds having 5 to 12 carbon atoms inclusive.

application Serial No. 200,112, filed December 9,

TABLE Efiect on induction period increase of gasoline No. Additive 5 1 N-(mixed amyl)-N-(p-hydmxyphenyDurca 755 N-n-octyl-N-(p-hydroxyphenyl)urea 520 Nn-dodecyl-N-(p-hydroxypenyl)urea 485 N-n-butyl-N'-(p-l1ydroxypl1cnyl) urea 255 N-n'octadecyl-N-(p-hydroxypheny1)ur 195 N-(p-hydroxyphenyl) urea 25 We have disclosed a number of embodiments of our invention and illustrated several methods whereby these materials can be prepared. However, our invention is not intended to be limited to the specific examples herein or to the means described herein for obtaining our novel compounds.

This application is a continuation-in-part of 1950, which is now abandoned.

We claim:

1. As new compositions of matter, ureas having the structure N'- (p-hydroxyphenyl) urea.

4. As a new composition of matter, N-dodecyl- N'- (p-hydroxyphenyl) urea.

EUGENE F. HILL. DAVID 0. DE FREE.

No references cited. 

1. AS NEW COMPOSITIONS OF MATTER, UREAS HAVING THE STRUCTURE 